3.2. Unit Conversions, Error, and Uncertainty http://www.ck12.org
3.2 Unit Conversions, Error, and Uncertainty
Lesson Objectives
- Differentiate between accuracy and precision as they relate to a given measurement.
- Describe the reliability of a measurement and how it can be expressed in terms of uncertainty.
- Distinguish between mass and weight and describe how mass and weight are determined.
- Understand the concept of volume and how it can be determined for various substances, including regularly
shaped and irregularly shaped solids. - Define density and perform density calculations.
- Describe how many significant figures there are in a given measurement, and be able to perform measurement
calculations involving numbers with significant figures.
Lesson Vocabulary
- meniscus: The curved upper surface of a liquid in a tube.
- estimate: A process of referencing a physical quantity in terms of a calibration or reference point.
- uncertainty: All measurements have an uncertainty equal to one half of the smallest difference between
reference marks. - accuracy: Describes how close an estimate is to a known standard.
- precision: Describes how close estimates are to one another.
- calibration: A method of setting or correcting a measuring device by matching it to known measurement
standards. - percent uncertainty: The ratio of the uncertainty to the measured value, multiplied by one hundred.
- percent error: An expression of the accuracy of a measurement, standardized to how large the measurement
is. - significant figures: Consist of all the certain digits in that measurement plus one uncertain or estimated digit.
- density: An expression of the mass of substance in terms of the volume occupied by the substance.
- mass: The quantity of inertia possessed by an object.
- weight: The gravitational force acting on a mass, as measured on a scale.
- Fahrenheit scale: The most commonly used scale in the United States, it defines the normal freezing point
and boiling point of water as 32°F and 212°F, respectively. - Celsius scale: The most commonly used scale around the world, it defines the normal freezing point and
boiling point of water as 0°C and 100°C, respectively. - Kelvin scale: Referred to as the absolute temperature scale, it defines absolute zero as the lowest theoretically
possible temperature.
Check Your Understanding
- What will it cost to carpet a room if the room is 10 feet wide and 20 feet long, and the price of carpet is $2.36
per ft^2?